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This paper introduces the vehicle routing problem with soft time windows (VRPSTW) in which problem definition differs from ones previously defined in literature. Branch-and-price approach is employed, resulting in a set partitioning master problem and its new subproblem. Novel techniques are consequently developed to solve this new subproblem. Experimental results report the comparisons of these solution techniques under the branch-and-price framework. The VRPSTW solutions have further been compared to the state-of-the-art literature, signifying the superiority of the VRPSTW on this issue. 相似文献
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《Economic Systems》2015,39(3):413-422
The constant proportion portfolio insurance (CPPI) strategy is one of the most popular asset allocation strategies employed by guaranteed-return financial products investors. Rebalance disciplines play an important role in determining the CPPI performance in practice. This paper examines whether the selection of rebalance rules affects CPPI strategy performance in the context of Chinese equity markets and, if so, in what pattern, and whether an optimal parameter of rebalance exists. We find that, (1) the three alternative rebalance disciplines – time discipline, market move discipline and lag discipline – are indifferent in affecting the performance of CPPI strategy; (2) in terms of optimal parameters of each rebalance rule, the optimal rebalancing period for the time discipline is 3 trading days, the optimal trading threshold of the market move discipline 4%, and the optimal lag factor of the lag discipline 6%. These optimal parameters are not influenced by the length of investment. 相似文献
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Using daily data from August 9, 2015, to July 7, 2020, this study examines the effects of economic policy uncertainty (EPU) on the returns of four cryptocurrencies: Bitcoin, Ethereum, Litecoin, and Ripple. To this end, two new measures of EPU (Twitter-based economic uncertainty and Twitter-based market uncertainty) are considered. A Granger causality test using the recursive evolving window approach shows a significant causality between the Twitter-based EPU measures and the BTC/USD exchange rate from October 2016 to July 2017. Moreover, a significant causality was noted from the EPU measures to the ETH/USD exchange rate from June 2019 to February 2020 and from the EPU measures to the XRP/USD exchange rate from January 2020 to February 2020. The Twitter-based EPU measures primarily positively affect the returns of the related cryptocurrencies during these periods. These results are robust to different measures of Twitter-based EPU and different econometric techniques. Potential implications, including the COVID-19 era, are also discussed. 相似文献
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滑动式车门的运动主要沿着车身侧围运动。因此,滑动式车门的运动相对铰链式车门的运动复杂,这就给设计带来了很大困难。由于三维设计软件的发展,可以在设计阶段通过建立虚拟的运动模型来指导设计。文章介绍通过运用UG NX5.0软件来建立某款车型的滑动车门运动模型,并对其应用进行分析。 相似文献
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滑动式车门的运动主要沿着车身侧围运动。因此,滑动式车门的运动相对铰链式车门的运动复杂,这就给设计带来了很大困难。由于三维设计软件的发展,可以在设计阶段通过建立虚拟的运动模型来指导设计。文章介绍通过运用UG NX5.0软件来建立某款车型的滑动车门运动模型,并对其应用进行分析。 相似文献
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采用随机共振解调微弱MFSK信号解决了传统解调方法误码率高的问题。
根据大噪声环境下信号能借助噪声能量发生随机共振这一理论,先将微弱MFSK信号通过双稳
态随机共振系统以提高其信噪比,对随机共振系统的输出信号用FFT来区分每段信号的载波
频率,最后依据判决准则解调MFSK信号。当信噪比较高时,可向信号中人为添加白噪
声来使之适用于该解调方法。MATLAB仿真结果表明,该方法能成功解调信噪比最低为
-23 dB的2FSK信号和-25 dB的8FSK信号,而这是传统相干解调方法所无法达到的。 相似文献
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